1. Field of the Invention
The present invention relates generally to spark advance in internal combustion engines and, more particularly, to a method for advanced crank spark with blend spark retard for an internal combustion engine.
2. Description of the Related Art
Environmental concerns have prompted government regulations to curb emissions from sources such as internal combustion engines in motor vehicles. For instance, the Clean Air Act of 1990 regulates maximum levels of hydrocarbons, carbon monoxide and oxides of nitrogen that may be emitted from a tailpipe of the motor vehicle. Also, California, because of its unique climate, has enacted its own stringent regulations.
In the motor vehicle, a catalytic converter is used for decreasing emissions from the engine before the exhaust gases exit through the vehicle's tailpipe. One technique for reducing emissions is to utilize a leaner air/fuel ratio, however, starting a cold engine requires a richer air/fuel ratio until the engine warms up. Another technique for reducing emissions is to increase the spark advance, but this is not always feasible during engine cranking. Therefore, there is a need in the art to provide a method of advancing the spark and then retarding the run spark to reduce emissions from the engine as soon as possible after the engine starts.